The present invention relates generally to an insulation assembly for use with cryogenic fuel tanks and more specifically to an insulation assembly having improved bonding characteristics.
Aerospace vehicle designs commonly utilize a variety of fuels to supply both launch and maneuvering power requirements. The quantity of fuel required for most missions, especially for launch requirements, often generates severe design constraints and can require considerable portions of vehicle size to be dedicated towards the carrying of fuel. The use of cryogenic fuels allows the fuels to be maintained in a liquid state rather than in their roomtemperature gaseous form. This allows a greater quantity of fuel to be stored in a smaller container. This, in turn, improves the design capabilities of aerospace vehicles.
Current cryogenic fuel tank technology for expendable launch systems such as the external tank of the space shuttle use spray-on foam insulation. This technology, however, does not commonly satisfy the strength and reusability requirements associated with multi-mission flight environments. Expendable launch systems are often not considered appropriate for integration into reusable launch vehicle designs. Reusable launch vehicle (RLV) designs often require such vehicles to carry the cryogenic fuel tanks through launch, on-orbit, and reentry. The cryogenic insulation (“cryoinsulation”) is required to reduce launch pad cryogen boil-off and thermally protect fuel tanks during ground servicing, launch, on-orbit, and reentry. In addition, the cryoinsulation must be robust enough to withstand repeated thermal cycling.
Cryoinsulation is applied to the exterior of the fuel tanks and can consist of a foam insulation layer and a thermal protection system (TPS) layer. It is desirable that the bond joint between the foam insulation layer and the thermal protection system be reliable to prevent peeling or other separation during the thermal cycling and other use related stresses of RLV applications. In addition, the cryoinsulation presents an opportunity for further protection of the fuel tank structure from damage due to on-orbit particle impact. Therefore, a cryogenic fuel tank system with an improved cryoinsulation design provides the opportunity to implement a variety of improvements to RLV design and application.
It would therefore be highly desirable to have a cryogenic fuel tank assembly with improved bonding characteristics within the cryoinsulation layers. It would further be highly desirable to develop a cryogenic fuel tank assembly with improved resilience to on-orbit particle impact.